I have a desperado on the way,bought it used and can't wait to try it. on the polishing the cover thing I think you guys are going at it the wrong way. I've never had any luck putting a shine on a urethane ball with polish.you have to bring the underlying grit up real high and get what you get with the polish OR use a compound with grit like Rough Buff or super duty or any other gritty compound and really lean on it on the spinner with a damp cloth and compound.
a little advice though,I've found on urethane that I like a little surface,urethane is all about hooking in the mids and a tame backend and roll.if you need polish then chances are you have the wrong ball.
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The harder I try the harder they fall